Comment 2 for bug 1500130

You seem to have both the ubuntu-desktop and kubuntu-desktop meta packages installed. This ends up causing an issue in the following way:

2015-09-27 04:04:50,957 DEBUG Installing 'baloo-kf5' (kubuntu-desktop PostUpgradeInstall rule)
2015-09-27 04:04:50,958 DEBUG Removing 'xscreensaver' (ubuntu-desktop PostUpgradeRemove rule)
2015-09-27 04:04:50,958 DEBUG Removing 'gnome-cups-manager' (ubuntu-desktop PostUpgradeRemove rule)
2015-09-27 04:04:50,958 DEBUG Removing 'powermanagement-interface' (ubuntu-desktop PostUpgradeRemove rule)
2015-09-27 04:04:50,958 DEBUG Removing 'deskbar-applet' (ubuntu-desktop PostUpgradeRemove rule)
2015-09-27 04:04:50,959 DEBUG Removing 'nautilus-cd-burner' (ubuntu-desktop PostUpgradeRemove rule)
2015-09-27 04:04:50,959 DEBUG Removing 'powermanagement-interface' (kubuntu-desktop PostUpgradeRemove rule)
2015-09-27 04:04:50,959 DEBUG Removing 'guidance-power-manager' (kubuntu-desktop PostUpgradeRemove rule)
2015-09-27 04:04:50,959 DEBUG Removing 'kde-guidance-powermanager' (kubuntu-desktop PostUpgradeRemove rule)
2015-09-27 04:04:50,960 DEBUG plugins for condition 'PostDistUpgradeCache' are '[]'
2015-09-27 04:04:50,960 DEBUG plugins for condition 'wilyPostDistUpgradeCache' are '[]'
2015-09-27 04:04:50,960 DEBUG plugins for condition 'from_vividPostDistUpgradeCache' are '[]'
2015-09-27 04:04:50,961 DEBUG Marking 'ubuntu-desktop' for upgrade
2015-09-27 04:04:52,575 DEBUG Marking 'kubuntu-desktop' for upgrade
2015-09-27 04:04:55,752 WARNING Can't mark 'kubuntu-desktop' for upgrade (E:Errore, pkgProblemResolver::Resolve ha generato delle interruzioni. Questo potrebbe essere causato da pacchetti bloccati.)
2015-09-27 04:04:56,060 DEBUG blacklist expr 'ubuntu-release-upgrader' matches 'ubuntu-release-upgrader-qt'
2015-09-27 04:04:56,060 DEBUG The package 'ubuntu-release-upgrader-qt' is marked for removal but it's in the removal blacklist

Looking at Aptlog.txt - I actually
 think this is just and issue with the kubuntu upgrade.